title: Evaluation of microchip capillary electrophoresis with external contactless conductivity detection for the determination of major inorganic ions and lithium in serum and urine samples.
abstract: The determination of inorganic ions in clinical samples in less than 90 seconds was demonstrated for microchip capillary electrophoresis using capacitively coupled contactless conductivity detection (C(4)D). Bare electrophoresis chips were used in combination with external electrodes which were part of the chip holder. In order to achieve the required selectivity and sensitivity, an optimization of the electrode layout was carried out. Limits of detection (LOD) of 1 microM for K(+), 1.5 microM for Ca(2+), 3 microM for Na(+), 1.75 microM for Mg(2+) and 7.5 microM for Li(+) were achieved. The determination of inorganic cations (NH(4)(+), K(+), Na(+), Ca(2+), Mg(2+)) and anions (Cl(-), NO(3)(-), SO(4)(2-), phosphate) in blood serum and urine samples was possible in one common electrolyte solution containing 15 mM L-arginine, 10.75 mM maleic acid and 1.5 mM 18-crown-6 at pH 5.90 by simply switching the separation voltage from positive to negative polarity. Lithium, present at significant levels when used for therapeutic purposes, can also be determined in blood serum using a slightly modified background electrolyte solution.
authors.affiliation: Department of Chemistry, University of Basel, Spitalstrasse 51, 4056, Basel, Switzerland.
authors.forename: Pavel
authors.initials: P
authors.lastname: Kubán
authors.forename: Peter C
authors.initials: PC
authors.lastname: Hauser
mesh_terms: D004553:Electric Conductivity; D004566:Electrodes; D046209:Electrophoresis, Microchip / Q000379:methods*; D008094:Lithium / Q000097:blood* / Q000652:urine*; D012680:Sensitivity and Specificity
chemical_list: D008094:Lithium